Electrochemical immunosensing for rapid glaucoma disease diagnosis through simultaneous determination of SPP1 and GAS6 proteins in ocular fluids

Abstract

The present work reports the development of the first electrochemical immunoplatform for the simultaneous determination of Osteopontin (SPP1) and Growth Arrest-Specific 6 (GAS6) proteins, novel glaucoma-related biomarkers, involving magnetic microparticles (μMPs), specific capture (CAb) and detection (DAb) antibodies further labeled with horseradish peroxidase (HRP) for the selective and sensitive sandwiching of both proteins and amperometric detection at disposable screen-printed carbon electrodes (SPCEs). The dual immunoplatform exhibited very attractive sensitivity, reproducibility and selectivity for the determination of both biotargets at the required clinical levels (LOD values of 6.0 and 59.0 pg mL􀀀 1 for SPP1 and GAS6, respectively). The analysis can be simply performed in less than 90 min. The dual immunoplatform was applied with very promising results to the analysis of aqueous humor samples from Implantable Collamer Lens (ICL), cataracts (CAT), and glaucoma (GLAU) patients. The diagnostic usefulness of SPP1 and GAS6 determination to discriminate between the three types of patients and its potential as a simple, rapid, and minimally invasive tool to support early diagnosis and follow-up of GLAU disease was proved. In addition, a proof-of-concept test using tear samples from a healthy volunteer supports the possibility of detecting these markers in this type of sample.